Chimpanzee nesting patterns in savanna habitat: Environmental influences and preferences

Abstract

Data on chimpanzee (Pan troglodytes) nesting patterns were collected in Issa, Ugalla, western Tanzania. Ugalla is one of the driest, most open, and seasonal habitats inhabited by chimpanzees. We investigated the physical characteristics of nests and trees used for nesting to understand environmental influences on nest building and identify the characteristics preferred by the chimpanzees and the basis for such preferences. We analyzed 2,167 nests and 1,523 nesting trees. Most nests were built in the middle section of the tree crown and close to the tree trunk, and used a single tree in construction. Some physical characteristics of nests (e.g., distance from tree trunk) seemed to be the result of constraints imposed by tree structure. Issa chimpanzees preferred tall trees with high first branches for nesting supporting the hypothesis that elevated height of a sleeping place is a predator defense strategy. The height from the ground to the first branch showed less variation than either tree height or crown height and correlated weakly with tree height, suggesting that height from the ground to the first branch may be a more important factor than tree height alone in selecting a tree in which to nest. As in other study sites, the chimpanzees used tree species in proportions that did not correspond to their abundance suggesting tree species preference. We report for the first time that chimpanzees directionally oriented their nests and propose that this may be to maximize sunlight. We compare our data to those of other chimpanzee study sites.

Nest-Building Behaviour by Chimpanzees (Pan troglodytes verus) in the Non-Protected Area of Diaguiri (Kedougou, Senegal): Implications for Conservation

“…The selection of nesting site, nest height and nest-bearing trees by chimpanzees described by several authors [Basabose and Yamagiwa, 2002;Furnichi and Hashimoto, 2004; and O 'Malley, 2008;Koops et al, 2012;Hernandez-Aguilar et al, 2013;Ndiaye et al, 2013b;Hakizimana et al, 2015] are also illustrated in the nesting behaviour of chimpanzees in Diaguiri. In this area, chimpanzees most often nested in woodland and grassland with isolated trees, while in Assirik, within the NKNP, chimpanzees nested less frequently in these habitats [Pruetz et al, 2008].…”

“…Although no single characteristic has been found sufficient for explaining preferences in terms of nest tree species, nest tree selectivity has been linked generally to physical characteristics of the trees [Furnichi and Hashimoto, 2004;Hernandez-Aguilar, 2006;Ndimuligo, 2007;Stanford and O'Malley, 2008;Koops et al, 2012;Hernandez-Aguilar et al, 2013;Carvalho, 2014]. In light of the tremendous variation in nesting tree characteristics, managers of natural resources need to take account of information on nesting tree preference by chimpanzee populations.…”

“…Weaned individuals of all great ape species build nests in which they sleep at night or sometimes rest during the day. Typically a nest is constructed, immediately used and abandoned the next morning [Kühl et al, 2008;Hernandez-Aguilar et al, 2013]. Nests can remain visible in the habitat for several weeks or months after construction and use.…”

Nest Grouping Patterns of Bonobos (Pan paniscus) in Relation to Fruit Availability in a Forest-Savannah Mosaic

“…The deep ancestry of this trait has possible implications for our understanding of the cognitive evolution of early hominoids [1], as it permits higher-quality sleep by providing thermoregulation [2], [3], reduced vulnerability to predators [2], [4], [5], more comfortable sleeping postures [4], [6], [7], and protection against pathogens [2], [4], [8]. The impact of environmental factors on the location of great ape nests has been the subject of a number of studies [6], [9]–[18], and nest counts are frequently used to estimate ape population density [19]–[29]. However the functionality of great ape nesting sites in relation to the dynamics of their social organization has been much less well-documented [1].…”

An Evaluation of Nest-Building Behavior by Sanctuary Chimpanzees with Access to Forested Habitats

“…At Fongoli, 3% of the nests were located on the ground [Pruetz et al, 2008], and when this site was compared to Assirik, it was concluded that nest height was related to presence or absence of large carnivores that may prey on the chimpanzees, as most predators had been exterminated at the Fongoli site. With no predators in the captive environment, this may be another explanation for Chimp Haven's chimpanzees nesting most often on the ground [McGrew, 2004;Stewart et al, 2011;Hernandez-Aguilar et al, 2013].…”